Plot / Plot3D

- I was getting sick of  `x y / (x ^ 2 + y ^ 2 + 1)` and decided to change it. `Exp[x] Cos[y]` is `Re[Exp[x + I y]]`. It evaluates slightly faster and looks smoother.

- `Plotpoints` was actually `1 + Plotpoints`, which I've corrected along with the error message.